Comparative investigation of liquid film thickness and interfacial wave properties of swirling gas-liquid flows

The liquid film in swirling flows plays an important role in mass, momentum and heat transfer, whose properties differ from those in non-swirling regimes. In this paper, we employ the image processing and statistical analysis to compare the liquid film thickness and wave properties of swirling gas column, swirling intermittent and swirling annular flow. The results indicate that the film thickness is intimately linked to the flow regimes, i.e., uniform in swirling gas column flow, gradual thickening in swirling intermittent flow, and increasing up to a maximum point and decreasing thereafter in swirling annular flow. Additionally, the wave frequency is proportional to j_g but inversely proportional to j_l in swirling gas column flow, which is to the contrary in swirling intermittent flow. In swirling annular flow, the waves show less correlation at a finite time and the frequency decreases with j_g, but the influence of j_l depends on flow distance.